1. Field of the Invention
The present invention provides methods for identifying agents that prevent restenosis, and the use of one or more agents identified in the screen, including without limitation colchicine analogs as defined herein, in the treatment or prevention of restenosis and so relates to the fields of biology, molecular biology, chemistry, medicinal chemistry, pharmacology, and medicine.
2. Description of Related Disclosures
The success of stents in balloon angioplasty has been limited by thrombotic complications and restenosis of the vessel wall, both of which occur as a result of normal injury and repair processes. Anti-platelet drugs and procedural anticoagulation have reduced the incidence of in-stent thrombosis, while drug-eluting stents have significantly reduced the incidence of restenosis. Currently approved drugs used on drug-eluting stents (paclitaxel, rapamycin) are strongly antiproliferative, effectively inhibit smooth muscle proliferation and block neointimal hyperplasia. Antiproliferative drugs, however, may delay or prevent complete healing of the injured vessel. Accordingly, the perpetuation of the wounded vessel can result in late loss (progressive loss of vessel diameter due to neointimal thickening) and late thrombosis, increasing the frequency of follow-up target lesion revascularization procedures, and thus reducing the effectiveness of stents coated with such drugs.
The biological processes that contribute to restenosis and late stage thrombosis include platelet and inflammatory cell recruitment and activation, cell proliferation and migration, vascular remodeling, and compromised re-endothelialization with reduced endothelial cell function. Inhibition of proliferation (e.g. smooth muscle cells, inflammatory cells) is a key process, as the drugs that have been successfully employed in drug-eluting stents (e.g. rapamycin, paclitaxel, everolimus) are strong anti-proliferatives.
Drugs that have been tested on drug eluting stents include agents from several categories: anti-proliferative (paclitaxel, actinomycin D, 17β-estradiol, imatinib mesylate), anti-proliferative/immunosuppressive (rapamycin, FK-506, mycophenolic acid), anti-inflammatory (methylprednisolone, dexamethasone, tranilast), anti-thrombotic (hirudin, iloprost), and others (rosiglitazone) (Abizaid, 2004, D'Amato, 1994, Serruys, 2004, Sousa, 2003a, 2003b). While paclitaxel, rapamycin and everolimus have been shown to be effective and approved for clinical use, other compounds, including some from the same classes have failed (e.g. actinomycin D, mycophenolic acid). Blocking inflammatory processes alone (e.g. with glucocorticoids) has not been effective, although inflammatory mediators and growth factors produced by recruited leukocytes and activated cell types do regulate vascular cell functions and can affect the recovery and repair process.
One of the major health risks of approved drug eluting stents, which are coated with taxol or rapamycin, is late thrombosis, which can lead to serious complications including death months to years following stenting procedure. Current treatment to prevent stent-related thrombosis is the use of oral anti-thrombotic agents such as Plavix, which cannot be maintained long term due to side effects or due to other medical procedures such as surgery where anti-thrombotic agents are contraindicated. Since endothelial cells play a key role in controlling thrombosis and fibrinolysis, and provide a non-procoagulant surface, it is believed that the main cause for the late thrombosis is incomplete re-endothelialization on the stented site. Unfortunately, owing to the complex biological processes that affect the function of stents in vivo, there have been no methods developed to date for the efficient identification and use of agents that would be most effective in inhibiting restenosis without compromising complete healing of the wounded vessel.
Human primary cell-based assay systems (BioMAP® Systems) that model in vitro the complex biology of human disease, including biology relevant to inflammation and restenosis, and which can be used for screening and development of drugs eliciting complex biological activities, have been developed: see U.S. Pat. Nos. 6,656,695 and 6,763,307 and PCT publication Nos. 01/67103, 03/23753, 04/22711, 04/63088, 04/94609, 05/23987, 04/94992, 05/93561, each of which is incorporated herein by reference. BioMAP Systems are capable of detecting and distinguishing activities of a broad range of mechanistically diverse compound classes, including anti-proliferative drugs, immunosuppressive drugs, anti-inflammatory drugs etc. For example, see Kunkel et al. (2004) Assay Drug Dev Technol. 2:431-41; and Kunkel et al. (2004). FASEB J. 18:1279-81.
Activity profiling of compounds, including experimental compounds as well as drugs approved for human or veterinary use, in BioMAP Systems, provides an enhanced understanding of the mechanism of action of compounds and allows the identification of compounds which are suitable for a particular therapeutic use, based on the favorable combinations of biological activities which these compounds induce in BioMAP Systems.
There remains a need for stents and other devices intended for in vivo use with better agents and combination of agents to prevent and treat restenosis. The present invention meets these needs.